Membrane free fuel cell

Abstract

The invention is directed to a fuel cell comprising an anode and a cathode immersed in an electrolyte in the presence of a reductant and oxidant, wherein the distinguishing feature is that all of the elements of the fuel cell communicate freely with each other and there is no membrane or other separator between the anode and the cathode.

1. A fuel cell comprising:
 (i) an anode configured and arranged for electro-oxidizing an anode reductant; 
 (ii) a cathode configured and arranged for electro-reducing a cathode oxidant; and 
 (iii) an electrolyte in solution contained within a single compartment; wherein the anode and cathode are spaced apart and reside in the single compartment containing the electrolyte; and wherein the electrolyte, reductant and oxidant freely communicate with the anode and the cathode;
 wherein the cathode comprises a porous current collector comprising an electrical conducting material in contact with a multitude of domains, each domain containing:
 a) a redox catalyst; and 
 b) an electron transport mediator; 
 
 wherein the redox catalyst and electron transport mediator are in fluid association with each other within the domain and wherein the redox catalyst and the electron transport mediator are bounded in the domain by the porous current collector and a containment material, and 
 wherein said containment material is a film comprised of materials selected from the group consisting of: silica, titania, alumina, polyesters, polyamides, polyimides, fluoropolymers, polyelectrolytes, organosubstituted silica, silicones, organosubstituted titania and organo metal oxides. 
 
 
     
     
       2. A fuel cell comprising:
 (i) an anode configured and arranged for electro-oxidizing an anode reductant; 
 (ii) a cathode configured and arranged for electro-reducing a cathode oxidant; and 
 (iii) an electrolyte in solution contained within a single compartment; wherein the anode and cathode are spaced apart and reside in the single compartment containing the electrolyte; and wherein the electrolyte, reductant and oxidant freely communicate with the anode and the cathode;
 wherein the anode comprises a porous current collector comprising an electrical conducting material, in contact with a multitude of domains, each domain containing:
 a) a redox catalyst; and 
 b) an electron transport mediator; 
 
 wherein the redox catalyst and electron transport mediator are in fluid association with each other within the domain and wherein the redox catalyst and the electron transport mediator are bounded in the domain by the porous current collector and a containment material, and wherein said containment material is a film comprised of materials selected from the group consisting of: silica, titania, alumina, polyesters, polyamides, polyimides, fluoropolymers, polyelectrolytes, organosubstituted silica, silicones, organosubstituted titania and organo metal oxides. 
 
 
     
     
       3. A fuel cell according to either of  claims 1  or  2  wherein the diameter of the domain is less than 100 μm. 
     
     
       4. A fuel cell according to either of  claims 1  or  2  wherein the porous current collector comprises an electrical conducting material. 
     
     
       5. A fuel cell according to either of  claims 1  or  2  wherein the electrical conducting material is selected from the group consisting of: carbon paper, carbon paste, carbon nanotubes, carbon particles, conducting polymers, noble metal particles and conducting metal oxide particles. 
     
     
       6. A fuel cell according to either of  claims 1  or  2  wherein the redox catalyst is an enzyme. 
     
     
       7. A fuel cell according to  claim 6  wherein the enzyme is an oxido-reductase. 
     
     
       8. A fuel cell according to  claim 1  wherein the redox catalyst is laccase. 
     
     
       9. A fuel cell according to either of  claims 7  or  2  wherein the electron transport mediator is selected from the group consisting of: quinones, hydroquinones, metalloorganic complexes, conjugated unsaturated acyclic and cyclic molecules, metal ions and biological electron carriers. 
     
     
       10. A fuel cell comprising:
 (i) an anode configured and arranged for electro-oxidizing an anode reductant; 
 (ii) a cathode configured and arranged for electro-reducing a cathode oxidant; and 
 (iii) an electrolyte in solution contained within a single compartment; wherein the anode and cathode are spaced apart and reside in the single compartment containing the electrolyte; and wherein the electrolyte, reductant and oxidant freely communicate with the anode and the cathode;
 wherein the anode or the cathode comprises a porous current collector comprising an electrical conducting material in contact with a multitude of domains, each domain containing:
 a) a redox catalyst; and 
 b) an electron transport mediator; 
 
 
 wherein the redox catalyst and electron transport mediator are in fluid association with each other within the domain and wherein the redox catalyst and the electron transport mediator are bounded in the domain by the porous current collector and a containment material, and wherein the electron transport mediator is 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonate). 
 
     
     
       11. A portable electronic device comprising the fuel cell of any of  claims 1 ,  2 , or  10 . 
     
     
       12. A fuel cell according to either of  claims 1 ,  2 , or  10 , wherein the redox catalyst catalyzes a redox reaction involving at least one reductant selected from the group consisting of: hydrogen, alcohols, carbohydrates, carboxylic acids and carboxylic esters. 
     
     
       13. A fuel cell according to  claim 12  wherein the carbohydrate is glucose. 
     
     
       14. A fuel cell according to  claim 12 , wherein said alcohol is methanol. 
     
     
       15. A fuel cell according to  claim 12 , wherein said carboxylic acid is formic acid. 
     
     
       16. A fuel cell according to  claim 12 , wherein said carboxylic ester is methyl formate.